The present invention relates to a variable-capacity liquid charging method and apparatus and more specifically to a method and an apparatus for charging a specified amount of liquid into open containers, which are empty capsules before being sealed with liquid in the process of making liquid-filled capsules.
In recent years, an ever-increasing variety of tobacco products are coming into market and, in the field of cigarette filters also, various kinds of filter products are being proposed.
For example, there is a cigarette filter loaded with a small capsule which, during smoking, is broken by pressure to let liquid in the capsule seep into the filter.
In such a filter, the liquid in the capsule may include water, perfume or other substances to improve taste and smell of the tobacco. By changing the liquid contents, it is possible to provide cigarettes with a variety of tastes meeting a growing diversity of consumers' needs.
A common method of making such filters involves filling the liquid into a container or capsule with one end open and hermetically sealing the opening with a lid.
A conventional technique for charging the liquid into the container consists in: installing the container with its opening facing up in a bottomed recess formed in the upper surface of a tray; positioning the tray at a specified location; and loading into the container a specified amount of liquid by a plunger pump which is located above the tray and can change its stroke to adjust the amount of liquid to be charged.
Such a liquid charging facility, however, has a very low efficiency as only one container is charged with liquid during each stroke of the pump. Therefore, to fill a large number of containers at a time requires arranging many pumps in parallel, which in turn increases not only the cost of the liquid charging equipment but also the design complexity, making the maintenance difficult.